51^ 



4.0 RESULTS 



To chronicle the events of the Portland Disposal Site Capping Demonstration 

 Project, the results of the comprehensive field sampling and monitoring program are 

 summarized in this section. The results of the five independent data collection efforts 

 between August 1995 and February 1997 are presented below, including 1) die Royal 

 River coring survey (Section 4.1); 2) the August 1995 baseline survey at the PDS (Section 

 4.2); 3) the expanded February 1996 baseline survey (Section 4.3); 4) the pseudo-UDM 

 precap survey (Section 4.4); and 5) the CDM postcap survey (Section 4.5). In addition, 

 results of the additional analysis of Royal River cores are presented (Section 4.6), and 

 finally, results of the statistical analyses conducted on the analysis of all of the coring data 

 (Section 4.7) 



4.1 Royal River Sediment Coring 



The coring survey conducted in the Royal River in August 1995 provided the 

 information necessary to be able to track and differentiate sediments on the PDS seafloor, 

 essential to the success of the Portland Disposal Site Capping Demonstration Project. The 

 estuarine envirormient with distinct sediment characteristics in the brackish and marine 

 reaches, the moderate volume of dredged material, and the location of the dredging area 

 relative to PDS made the Royal River a strong candidate for the capping demonstration. 

 The 30 collected cores (Figure 2-4) provided a cross section of the material to be dredged 

 from the Royal River. 



The sampled reaches of the river were classified to show the sediment 

 characteristics of three estuarine zones (upper, middle, and outer) within the Royal River. 

 A general description of the lithologies recovered in the cores is provided in Section 4.1.1, 

 and then results from the more detailed analysis of the potential tracers evaluated from the 

 cores is provided in Section 4.1.2. Core descriptions are provided in Appendix A. 



4.1.1 Sediment Characterization 



Several lithologic units were recovered from each of the three esmarine zones 

 within Royal River. The upper zone of the river is in the transition area between 

 freshwater and brackish environments that extends from the base of the falls to the eastern 

 margin of the anchorage area. The material recovered from the upper zone, representative 

 of the pseudo-UDM material to be dredged, consisted primarily of a subtidal to intertidal 

 mudflat deposit. However, the material collected in Core RR-15 was very sandy, which 

 may be attributable to past anthropogenic activity. Cores obtained from the middle and 

 outer zones of the river, representing CDM, contained higher concentrations of sand, with 

 the extreme outer cores (RR-21 and RR-22) containing layers of fine to medium sand. The 

 outer region contained both sand flat deposits and flood/tidal charmel deposits. Flood/tidal 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



